Power train

Abstract

A power train for use in a motor vehicle has an infinitely variable transmission with two sheaves and a belt which is trained over the sheaves. The sheaves have fixed and axially movable flanges, and one of the sheaves is driven by the engine through a torque sensor. A first hydraulic circuit has a first pump which can supply pressurized oil to the hydraulic motors for the axially movable sheaves at a pressure determined by the torque sensor. A second hydraulic circuit has a second pump serving to supply pressurized oil to a further motor which varies the ratio of the transmission and to two friction clutches between the second sheave and an output member. The pressure of oil in the second circuit is determined by a pressure regulating valve which is adjustable by a control unit in dependency on one or more parameters of the engine. A first distributing valve can connect the second pump with the further motor and/or with one of the two clutches, and a second distributing valve can connect the first distributing valve with the one or the other clutch. One of the clutches can drive the output member in a first direction, and the other clutch can drive the output member by way of a planetary in a second direction counter to the first direction.

I claim: 
     
       1. A power train, particularly for use in motor vehicles, comprising at least one engageable and disengageable clutch; fluid-operated means for engaging said at least one clutch; an infinitely variable transmission in series with said at least one clutch, said transmission including a first rotary sheave arranged to receive torque from a prime mover, a second rotary sheave connected with said at least one clutch, and an endless flexible torque transmitting element trained over said sheaves, each of said sheaves comprising a first flange and a second flange movable axially toward and away from the respective first flange, said transmission further comprising first and second fluid-operated motors for the respective second flanges; a torque sensor connected with the prime mover; means for varying the ratio of said transmission; at least one source of pressurized fluid; a first circuit connecting said at least one source with said motors and with said torque sensor; and a second circuit connecting said at least one source with said varying means and/or with said engaging means, said second circuit comprising an adjustable pressure regulating device. 
     
     
       2. The power train of claim 1, wherein at least one of said motors includes a cylinder and piston unit. 
     
     
       3. The power train of claim 1, wherein said varying means comprises a further fluid-operated motor having means for moving the second flange of one of said sheaves, said pressure regulating device comprising a valve and further comprising at least one control unit having means for adjusting said valve as a function of at least one of a plurality of different parameters. 
     
     
       4. The power train of claim 3, wherein said at least one parameter is a parameter of the prime mover. 
     
     
       5. The power train of claim 3, further comprising means for selectively connecting said valve with said engaging means or with said further motor. 
     
     
       6. The power train of claim 5, wherein said connecting means is adjustable to connect said valve with said engaging means preparatory to start of transmission of torque from the prime mover to said transmission. 
     
     
       7. The power train of claim 5, wherein said at least one clutch is a friction clutch and said connecting means is adjustable to connect said valve with said further motor and to connect said engaging means in said first circuit immediately or at least shortly upon complete engagement of said at least one clutch. 
     
     
       8. The power train of claim 5, wherein said connecting means comprises a distributing valve in said circuits, said distributing valve being connected with said engaging means and with said varying means. 
     
     
       9. The power train of claim 8, wherein said distributing valve is further connected with the valve of said pressure regulating device. 
     
     
       10. The power train of claim 8, wherein said distributing valve is a 5/3-way valve. 
     
     
       11. The power train of claim 8, wherein said distributing valve is a 5/2-way valve. 
     
     
       12. The power train of claim 8, wherein said prime mover includes a fuel consuming engine and said distributing valve is connected with and is adjustable by said at least one control unit as a function of at least one of said plurality of different parameters, said parameters including the rate of delivery of fuel to the engine, the RPM of the engine, the RPM of the second sheave, and the position of a gear shift member for the engine. 
     
     
       13. The power train of claim 3, wherein said prime mover comprises a fuel consuming engine and said valve is an electrically adjustable valve, said parameters including the rate of delivery of fuel to the engine, the RPM of the engine, the RPM of the second sheave and the position of a gear shift member for the engine. 
     
     
       14. The power train of claim 1, wherein said at least one source includes a first pump in said first circuit and a second pump in said second circuit. 
     
     
       15. The power train of claim 14, further comprising a pressure relief valve in said second circuit between said second pump and a valve of said pressure regulating device. 
     
     
       16. The power train of claim 1, comprising two fluid-operated engageable and disengageable clutches in series with said second sheave, said engaging means including means for selectively engaging one of said clutches at a time and further comprising a planetary connected with and arranged to receive torque from one of said clutches. 
     
     
       17. The power train of claim 16, further comprising a rotary output member, said one clutch having means for rotating said output member through said planetary in a first direction and the other of said clutches having means for rotating said output member in a second direction counter to said first direction. 
     
     
       18. The power train of claim 16, further comprising means for selectively connecting said pressure regulating device with said engaging means or with said varying means, said connecting means comprising a first distributing valve and said engaging means comprising a second distributing valve which is adjustable to connect said first distributing valve with the one or the other of said clutches. 
     
     
       19. The power train of claim 18, wherein said second distributing valve is a 4/2-way valve. 
     
     
       20. The power train of claim 16, wherein at least one of said clutches comprises a substantially piston-like portion which is movable in a first direction to effect the engagement and in a second direction to effect the disengagement of the at least one clutch, and further comprising means for yieldably biasing said substantially piston-like portion in said first direction. 
     
     
       21. The power train of claim 20, wherein said biasing means comprises at least one spring. 
     
     
       22. The power train of claim 1, wherein said torque sensor comprises a valve connected in said first circuit and having at least fluid discharging outlet, and further comprising a pressure regulating valve in said outlet. 
     
     
       23. The power train of claim 22, wherein said at least one clutch includes a substantially piston-like portion which is movable in a first direction for engagement and in a second direction for disengagement of said at least one clutch, and means for yieldably biasing said substantially piston-like portion in said first direction with a predetermined force, said pressure regulating valve being operative to maintain the fluid pressure therein at a value such to at least substantially compensate for said predetermined force. 
     
     
       24. The power train of claim 1, wherein said varying means comprises a further fluid-operated motor arranged to move the second flange of said first sheave and operating in parallel with said first motor. 
     
     
       25. The power train of claim 1, wherein said transmission further comprises means for yieldably biasing one of said second flanges toward the respective first flange. 
     
     
       26. The power train of claim 25, wherein said one second flange is the second flange of said second sheave. 
     
     
       27. The power train of claim 25, wherein said biasing means comprises at least one spring 
     
     
       28. The power train of claim 25, wherein said biasing means comprises a package of dished springs.